Method and apparatus for allocating wireless resource and wireless network system

CROSS REFERENCE TO RELATED APPLICATION

p-0002This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2008-103643, filed on Oct. 22, 2008, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

p-00031. Field

p-0004The following description relates to a network resource allocation technique, and more particularly, to a resource allocation apparatus and method which maintains quality of service (QoS) in a wireless communication network.

p-00052. Description of the Related Art

p-0006WiMedia logical link control protocol (WLP) for a wireless network provides a service interval based medium access slot allocation (SIMA) technique for reliable quality of service (QoS) in a time division multiple access (TDMA)-based system employing distributed reservation protocol (DRP).

p-0007SIMA technique uses a traffic specification (TSPEC) of an application to obtain the maximum allowable values of a service rate and a delay time and cyclically performs medium access slot (MAS) allocation to satisfy delay bound.

p-0008For efficient MAS allocation, an iso-zone based SIMA scheme has been introduced which organizes a superframe into a plurality of allocation zones, organizes the allocation zones into iso-zones, each of which has an index value, and allocates medium access slots (MAS) to k number of iso-zones. However, the SIMA scheme has a drawback in that service intervals may not be uniform during MAS allocation depending on the number of iso-zones k. Furthermore, even if the superframe contains sufficient idle MAS for satisfying QoS required by a higher TSPEC, since the iso-zone based SIMA scheme cannot allocate further MAS, then there are limits to the efficient resource allocation management that can be obtained.

SUMMARY

p-0009Accordingly, in one aspect, there is provided a wireless resource allocation apparatus and method which makes service intervals more uniform during medium access slot (MAS) allocation to satisfy a traffic delay requirement and thereby improves required quality of service (QoS).

p-0010Also, there is provided a wireless resource allocation apparatus and method which increases distribution rate of MAS for minimizing idle MAS and thereby improves efficiency of resource distribution.

p-0011According to an aspect, there is provided a wireless resource allocation method in a wireless network, including calculating the number of medium access slots (MAS) to be allocated to at least one of a plurality of divided zones of at least one superframe, designating a reference location for MAS allocation to divided zones from the plurality of divided zones of the superframe based on the obtained number of medium access slots, and allocating the medium access slots to the divided zones based on information of designated reference location.

p-0012The designating of the reference location may designate the reference location such that an interval between the divided zones to which the medium access slots are to be allocated is minimized.

p-0013The calculating of the number of medium access slots may include calculating the amount of data included in a unit superframe based on service rate information, identifying the number of superframes based on the calculated amount of data, calculating a total channel time using the identified number of superframes, and calculating the number of medium access slots by dividing the total channel time by a time allocated to the medium access slots.

p-0014According to another aspect, there is provided a wireless resource allocation apparatus in a wireless network system, including a medium access slot (MAS) number calculating unit to calculate medium access slots to be allocated to at least one of a plurality of divided zones of at least one superframe, and a MAS allocating unit to designate a reference location for MAS allocation to divided zones among the plurality of divided zones of the superframe based on the calculated number of medium access slots and to perform the MAS allocation.

p-0015The MAS allocating unit may designate the reference location based on the calculated number of medium access slots such that an interval between the divided zones to which the medium access slots are to be allocated is minimized.

p-0016The MAS number calculating unit may include a data amount calculating unit to calculate the amount of data included in a unit superframe based on service rate information, a frame number identifying unit to identify the number of superframes based on the calculated amount of data, a time calculating unit to calculate a total channel time using the identified number of superframes, and a slot calculating unit to calculate the number of medium access slots by dividing the calculated total channel time by a time allocated to the medium access slots.

p-0017The MAS allocating unit may calculate the number of medium access slots to be allocated to a divided zone at the reference location and compares the calculated number of medium access slots to an allowable maximum number of medium access slots to be allocated to a divided zone of the superframe, and perform MAS allocation to another divided zone adjacent to the divided zone at the reference location when the calculated number of medium access slots is greater than the maximum number of medium access slots.

p-0018According to still another aspect, there is provided a wireless network system including a media access control (MAC) hierarchy control unit to calculate the number of medium access slots to be allocated to one of a plurality of divided zones of at least one superframe, to designate a reference location for MAC allocation to divided zones among the plurality of divided zones of the superframe based on the calculated number of medium access slots and to perform the MAC allocation.

p-0019The MAC hierarchy control unit may designate the reference location based on the calculated number of medium access slots such that an interval between the divided zones to which the medium access slots are to be allocated is minimized.

p-0020The MAC hierarchy control unit may calculate the number of medium access slots to be allocated to a divided zone at the reference location and compares the calculated number of medium access slots to an allowable maximum number of medium access slots to be allocated to a divided zone of the superframe, and perform MAS allocation to another divided zone adjacent to the divided zone at the reference location when the calculated number of medium access slots is greater than the maximum number of medium access slots.

p-0021Other features will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the attached drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0022<figref idrefs="DRAWINGS">FIG. 1</figref> is a block diagram illustrating an exemplary wireless resource allocation apparatus.

p-0023<figref idrefs="DRAWINGS">FIG. 2</figref> is a diagram illustrating examples of a reference location designated based on the number of medium access slots to be allocated to a divided zone.

p-0024<figref idrefs="DRAWINGS">FIG. 3</figref> is a flowchart illustrating an exemplary method of calculating the number of medium access slots.

p-0025<figref idrefs="DRAWINGS">FIG. 4</figref> is a flowchart illustrating an exemplary method of allocating medium access slots.

p-0026<figref idrefs="DRAWINGS">FIG. 5</figref> is a flowchart illustrating in detail an exemplary method of allocating medium access slots in a superframe.

p-0027Elements, features, and structures are denoted by the same reference numerals throughout the drawings and the detailed description, and the size and proportions of some elements may be exaggerated in the drawings for clarity and convenience.

DETAILED DESCRIPTION

p-0028The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses and/or systems described herein. Various changes, modifications, and equivalents of the systems, apparatuses and/or methods described herein will suggest themselves to those of ordinary skill in the art. Descriptions of well-known functions and structures are omitted to enhance clarity and conciseness.

p-0029<figref idrefs="DRAWINGS">FIG. 1</figref> is a block diagram illustrating an exemplary wireless resource allocation apparatus. The apparatus includes a medium access slot (MAS) number calculating unit <b>100</b> and a medium access slot (MAS) allocating unit <b>110</b>.

p-0030The MAS number calculating unit <b>100</b> calculates the number of medium access slots (MAS) allocated to one of a plurality of divided zones of a superframe.

p-0031The superframe is composed of time slots, i.e., the medium access slots (MASs), and is divided into a beacon zone and a data zone. MASs belonging to the beacon zone are utilized for beacon transmission of individual devices, and each MAS includes an information element field that performs negotiation for MAS allocation. In addition, MASs belonging to the data period include a command frame that performs negotiation for MAS allocation. The MAS number calculating unit <b>100</b> calculates the number of medium access slots to be included in the data period of the superframe.

p-0032To calculate the number of medium access slots to be allocated per superframe, the MAS number calculating unit <b>100</b> may consider at least one of a medium variable of traffic specification (TSPEC) for an application stream, a service rate, a physical speed of a corresponding ultra wide band (UWB), a preamble mode, an answer mode, and the size of a media access control (MAC) service data unit (MSDU).

p-0033More specifically, the MAS number calculating unit <b>100</b> includes a data amount calculating unit <b>102</b>, a frame number identifying unit <b>104</b>, a time estimating unit <b>106</b>, and a slot calculating unit <b>108</b>.

p-0034In one example, the MAS number calculating unit <b>100</b> should consider a service rate and an overhead for frame transmission to obtain the number of medium access slots to be allocated per superframe. A service rate is requested by a higher hierarchy. Since the service rate is data traffic throughput obtained without considering the overhead generated in actual data transmission, a traffic throughput higher than the service rate is required for practical communications between devices. In other words, to calculate the number of medium access slots per superframe for communications between devices, both the service rate and the overhead caused by a transmitted packet data unit (PDU) need to be considered.

p-0035The data amount calculating unit <b>102</b> first obtains the service rate from the TSPEC, and then calculates the total amount of data to be transmitted to a unit superframe for satisfying the service rate with respect to device application.

p-0036The frame number identifying unit <b>104</b> obtains the number of superframes by dividing the amount of data which has been obtained by the data calculating unit <b>102</b> by a MAC service data unit of a given size corresponding to the payload of a superframe.

p-0037The time estimating unit <b>106</b> first estimates a channel time based on the number of superframes obtained by the frame number identifying unit <b>104</b>, in consideration of an answer mode, a preamble mode, and the physical speed of a corresponding UWB. Subsequently, the time estimating unit <b>106</b> obtains the final total channel time by adding a request-to-send (RTS)/clear-to-send (CTS) and a guard time to the firstly estimated channel time. RTS/CTS is the minimum size of a packet of a CTS signal issued by a recipient to respond to an RTS signal.

p-0038The slot calculating unit <b>108</b> divides the obtained total channel time by the time allocated to a medium access slot to obtain the number of medium access slots.

p-0039The MAS allocating unit <b>110</b> designates a reference location for MAS allocation to divided zones among the plurality of divided zones of the superframe, based on the number of medium access slots calculated by the MAS number calculating unit <b>100</b>. Then, the MAS allocating unit <b>110</b> allocates medium access slots to the divided zones based on the reference location. The MAS allocating unit <b>110</b> allocates as many MASs as the calculated number to the divided zones of the superframe. Here, the MAS allocating unit <b>110</b> includes a reference location designating unit <b>115</b> for medium access slots to be evenly distributed in the superframe.

p-0040The reference location designating unit <b>115</b> identifies the number of divided zones to which medium access slots are allocated, according to the number of the medium access slots. The number of divided zones may be calculated in consideration of a service interval for satisfying a traffic delay requirement in accordance with the traffic specification. The reference location may be designated for the divided zones to which the medium access slots are to be allocated such that intervals between neighboring divided zones to which the medium access slots are to be allocated can be minimized.

p-0041Additionally, the MAS allocating unit <b>110</b> compares the calculated number of medium access slots by the MAS number calculating unit <b>100</b> to the maximum number of medium access slots which one divided zone of the superframe can accommodate. When the calculated number of medium access slots is greater than the allowable maximum number of medium access slots, the MAS allocating unit <b>110</b> allocates the medium access slots to a neighboring divided zone.

p-0042<figref idrefs="DRAWINGS">FIG. 2</figref> is a diagram illustrating examples of a reference location according to the number of medium access slots to be allocated to a divided zone.

p-0043In the conventional service interval based MAS allocation (SIMA) method, the order of use of the reference location is based on the priority of an iso-zone which is the divided zone to which MAS is to be allocated. In this conventional method, it is problematic that intervals between the divided zones are not equal to one another. When the intervals between the divided zones are not uniform, a service interval between each divided zone is lengthened. Therefore, for services requiring a short service interval, the allocation failure probability can consequently increase in a medium shared by service devices. To evenly distribute reservation zones according to strict service interval restrictions, as shown in <figref idrefs="DRAWINGS">FIG. 2</figref>, the reference location may be designated for the divided zones to which medium access slots participating in the reservation are to be allocated.

p-0044In <figref idrefs="DRAWINGS">FIG. 2</figref>, the number k of divided zones to which MASs are to be allocated is increased in rows. Individual columns indicate divided zones, some of which MASs are to be allocated to.

p-0045Since the zone <b>0</b> is a reserved for a beacon message, the superframe may be divided into 15 zones. For example, when k which is the number of divided zones to which medium access slots are to be allocated is 3, medium access slots may be allocated to zones <b>1</b>, <b>6</b>, and <b>11</b>. Where a divided zone has a service interval of 4,096 μs, a service interval can be at maximum 6*4,096 μs, and thus intervals between medium access slots allocated in the superframe, i.e. a difference between the maximum service interval and the minimum service interval can be minimized.

p-0046<figref idrefs="DRAWINGS">FIG. 3</figref> is a flowchart illustrating an exemplary method of calculating the number of medium access slots.

p-0047First, a service rate is obtained from TSPEC. Then, the total amount of data to be transmitted to a unit superframe for satisfying the service rate with respect to device application is calculated (operation <b>300</b>). The data to be transmitted to the unit superframe is divided by MSDU of a predetermined size corresponding to the payload of a superframe, and consequently the number of superframes is obtained (operation <b>310</b>).

p-0048The total channel time is primarily calculated based on the number of superframes, in consideration of an answer mode, a preamble mode, and a physical speed of a corresponding UWB (operation <b>320</b>). Then, a final total channel time is calculated by adding a guard time and RTS/CTS, which is the minimum packet size of a CTS signal from a recipient to respond to a RTS signal, to the primarily calculated total channel time (operation <b>330</b>).

p-0049The final total channel time is divided by the time allocated to each MAS so as to output the number of medium access slots to be allocated in the superframe (operation <b>340</b>).

p-0050<figref idrefs="DRAWINGS">FIG. 4</figref> is a flowchart illustrating an exemplary method of allocating medium access slots.

p-0051It is determined whether or not the calculated number of medium access slots is smaller than the maximum number of medium access slots that can be contained in a unit superframe (operation <b>400</b>). In one example, the maximum number of medium access slots that can be contained in a superframe may be 16*16, i.e. 256.

p-0052If the calculated number of medium access slots is smaller than the maximum number of medium access slots that can be contained, the calculated number is compared to a threshold value predetermined by MAC policy (operation <b>410</b>). When the calculated number of medium access slots is greater than the predetermined threshold value, a safe value of the superframe becomes false. This indicates that the number of medium access slots to be allocated in a superframe violates the MAC policy (operation <b>415</b>). On the other hand, if the calculated number of medium access slots is smaller than or equal to the threshold value predetermined by the MAC policy, the number of divided zones to which medium access slots are to be allocated, that is k, is set in consideration of a service interval (operation <b>420</b>).

p-0053In one example, where the number of medium access slots which one divided zone can contain is 16, if the number of medium access slots to be allocated to the divided zone is more than 16, all medium access slots cannot be allocated to the divided zone. Hence, when the number of medium access slots to be allocated is more than 16 (operation <b>430</b>), more divided zones to which the medium access slots are to be allocated are required (operation <b>435</b>). That is, when the number of medium access slots to be allocated is more than 16, k increases by 1.

p-0054In addition, when the number of medium access slots to be allocated is less than 16, k is compared to the maximum number, i.e. k_max, of divided zones to which medium access slots are to be allocated in the superframe (operation <b>440</b>).

p-0055When k is smaller than or equal to k_max, the medium access slots are allocated in the superframe (operation <b>450</b>). At this time, it is determined whether a divided zone to which medium access slots are to be allocated is available for allocation (operation <b>460</b>), and if the divided zone is available, the medium access slots are allocated thereto (operation <b>470</b>). Then, allocation of medium access slots to the next available divided zone is performed in the same superframe to which the medium access slots have been allocated (operation <b>480</b>).

p-0056Alternatively, if k is greater than k_max, there is no divided zone to which medium access slots can be allocated in the superframe. Thus, a shift to a neighboring superframe for allocation takes place (operation <b>443</b>). When the allocation is available in the neighboring superframe (operation <b>447</b>), medium access slots are allocated thereto (operation <b>470</b>). The allocation process returns to the superframe to which the medium access slots are allocated in operation <b>470</b> (operation <b>480</b>). Alternatively, if the neighboring superframe is not available for the allocation, a null value is returned.

p-0057<figref idrefs="DRAWINGS">FIG. 5</figref> is a flowchart illustrating in detail an exemplary method of allocating medium access slots in a superframe. The MAS allocation is conducted based on cyclic and uniform distribution. First, based on the number, i.e. k, of divided zones to which medium access slots are to be allocated out of a plurality of divided zones in a superframe, a reference location of the divided zones to which the medium access slots are to be allocated is identified (operation <b>500</b>). The designating of the reference location based on k is described above with reference to <figref idrefs="DRAWINGS">FIG. 2</figref>.

p-0058Based on information on the designated reference location, it is determined whether or not all medium access slots can be allocated in the present superframe (operation <b>510</b>). If the allocation is available, the medium access slots are allocated in the superframe, and an allocation location returns to the reference location of the superframe (<b>580</b>). On the other hand, when all medium access slots cannot be allocated in the present superframe, it is determined whether a neighboring superframe is available for allocation of medium access slots.

p-0059For example, it is assumed that a superframe is divided into sixteen zones and a ratio between the number of zones to which medium access slots are to be allocated and the remaining zones is calculated (operation <b>520</b>). That is, the ratio can be obtained by (16-k)/k. An initial value of an arbitrary number I is set as 0 (operation <b>530</b>), and the value of I is compared to the calculated ratio value (operation <b>540</b>).

p-0060The comparison is performed repeatedly until the value of I reaches the ratio value (operation <b>542</b>), and it is determined whether the superframe is available for the MAS allocation (operation <b>544</b>). When it is determined that the superframe is available, the MAS allocation is performed on the divided zones to which the medium access slots are to be allocated in the superframe (operation <b>580</b>). Alternatively, if the superframe is not available, a value of I is increased by 1 (operation <b>546</b>).

p-0061If the value of I is equal to or greater than the ratio value, this implies that the MAS allocation cannot be performed on a next divided zone in the same superframe any longer, and it is determined whether it is possible to proceed with the MAS allocation in another superframe (operation <b>550</b>). If the MAS allocation is possible, a shift from the present superframe to the next superframe is performed (operation <b>555</b>). When the superframe shift is not possible and k is smaller than the maximum number of the divided zones in the superframe, i.e., k_max(operation <b>560</b>), k is increased by 1 (operation <b>565</b>) and the process returns to operation <b>500</b>. When k is greater than k_max, a null value is returned.

p-0062In a wireless network system including a plurality of devices, each device transmits a beacon included in a beacon zone of a superframe to adjacent devices prior to data transmission. The beacon zone of each device contains a device identifier, beacon slot information, medium use history, and the like. The devices reserve different divided zones to which medium access slots are to be allocated, and receives corresponding medium access slots.

p-0063A media access control (MAC) hierarchy of the wireless network system obtains the number of medium access slots to be allocated to one divided zone out of a plurality of divided zones of a superframe, designates a reference location for MAS allocation in the superframe based on the obtained number of medium access slots, and performs the MAS allocation.

p-0064In this case, the MAC hierarchy identifies the number of divided zones to which medium access slots are to be allocated in the superframe based on the obtained number of medium access slots. Then, a reference location for the divided zones to which medium access slots are to be allocated is designated such that the intervals between the divided zones to which medium access slots are to be allocated can be minimized.

p-0065Also, the MAC hierarchy obtains the number of medium access slots to be allocated to a divided zone at the reference location and compares the obtained number of medium access slots to the allowable maximum number of medium access slots to be allocated in a divided zone of the superframe. If the comparison result shows that the obtained number of medium access slots is greater than the maximum number of medium access slots, the MAC hierarchy performs MAS allocation on another divided zone adjacent to the divided zone at the reference location.

p-0066As described above, media resource slots are cyclically allocated at uniform intervals for efficient use of medium resource in a wireless network system, so that more uniform service intervals can be formed. Consequently, efficient MAC allocation is possible, satisfying MAC-based quality of service (QoS) requirements.

p-0067In addition, the distribution rate of MASs can be increased to minimize the number of idle MASs.

p-0068The wireless resource allocation method described above can be implemented as a computer program. Also, the method may be recorded, stored, or fixed in one or more computer-readable media that includes program instructions to be implemented by a computer to cause a processor to execute or perform the program instructions. Examples of computer-readable media include magnetic media and optical media.

p-0069A number of exemplary embodiments have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.